\documentclass{article}

            \usepackage[utf8]{inputenc} 
            \usepackage[textheight = 24cm]{geometry} 
            \usepackage[font = sf, justification=raggedright]{caption} 
            \usepackage{array}
            \usepackage{hhline} 
            \usepackage[math]{cellspace}
            \cellspacetoplimit 4pt
            \cellspacebottomlimit 4pt

            \begin{document}

          \begin{table}
           \begin{minipage}[b]{0.35\textwidth}
           \mbox{}\par            
           \caption{Cellspace solution\hfill\vspace{2.5\baselineskip}}
            \begin{tabular}[b]{ >{\bfseries}l|*{6}{| >{$}Sc <{$}}}
             0 & \textbf{1} & \textbf{2} & \textbf{3} & \textbf{4} & \textbf{5} & \textbf{6}\\
            \hhline{=::======}
              1  & \frac{1}{1} & \frac{1}{2} & \frac{1}{3} & \frac{1}{4} & \frac{1}{5} & \frac{1}{6} \\
            \hhline{-||------}
              2  & \frac{2}{1} & \frac{2}{2} & \frac{2}{3} & \frac{2}{4} & \frac{2}{5} & \frac{2}{6} \\
            \hhline{-||------}
              3  & \frac{3}{1} & \frac{3}{2} & \frac{3}{3} & \frac{3}{4} & \frac{3}{5} & \frac{3}{6} \\
            \hhline{-||------}
              4  & \frac{4}{1} & \frac{4}{2} & \frac{4}{3} & \frac{4}{4} & \frac{4}{5} & \frac{4}{6} \\
           \hhline{-||------}
              5  & \frac{5}{1} & \frac{5}{2} & \frac{5}{3} & \frac{5}{4} & \frac{5}{5} & \frac{5}{6} \\
            \hhline{-||------}
              6  & \frac{6}{1} & \frac{6}{2} & \frac{6}{3} & \frac{6}{4} & \frac{6}{5} & \frac{6}{6} \\
            \end{tabular}
          \end{minipage}
           \everymath{\displaystyle}
            \begin{tabular}[b]{ >{\bfseries}l|*{6}{| >{$}Sc <{$}}}
             0 & \textbf{1} & \textbf{2} & \textbf{3} & \textbf{4} & \textbf{5} & \textbf{6}\\
            \hhline{=::======}
              1  & \frac{1}{1} & \frac{1}{2} & \frac{1}{3} & \frac{1}{4} & \frac{1}{5} & \frac{1}{6} \\
            \hhline{-||------}
              2  & \frac{2}{1} & \frac{2}{2} & \frac{2}{3} & \frac{2}{4} & \frac{2}{5} & \frac{2}{6} \\
            \hhline{-||------}
              3  & \frac{3}{1} & \frac{3}{2} & \frac{3}{3} & \frac{3}{4} & \frac{3}{5} & \frac{3}{6} \\
            \hhline{-||------}
              4  & \frac{4}{1} & \frac{4}{2} & \frac{4}{3} & \frac{4}{4} & \frac{4}{5} & \frac{4}{6} \\
           \hhline{-||------}
              5  & \frac{5}{1} & \frac{5}{2} & \frac{5}{3} & \frac{5}{4} & \frac{5}{5} & \frac{5}{6} \\
            \hhline{-||------}
              6  & \frac{6}{1} & \frac{6}{2} & \frac{6}{3} & \frac{6}{4} & \frac{6}{5} & \frac{6}{6} \\
            \end{tabular}
            \end{table}
\mbox{}
          \begin{table}
           \begin{minipage}[b]{0.3\textwidth}
           \mbox{}\par
          \caption{Arraystretch solution\hfill\vspace{6pt}}
          \renewcommand{\arraystretch}{1.667}
            \begin{tabular}[b]{ >{\bfseries}l|*{6}{| >{$}c <{$}}}
             0 & \textbf{1} & \textbf{2} & \textbf{3} & \textbf{4} & \textbf{5} & \textbf{6}\\
            \hhline{=::======}
              1  & \frac{1}{1} & \frac{1}{2} & \frac{1}{3} & \frac{1}{4} & \frac{1}{5} & \frac{1}{6} \\
            \hhline{-||------}
              2  & \frac{2}{1} & \frac{2}{2} & \frac{2}{3} & \frac{2}{4} & \frac{2}{5} & \frac{2}{6} \\
            \hhline{-||------}
              3  & \frac{3}{1} & \frac{3}{2} & \frac{3}{3} & \frac{3}{4} & \frac{3}{5} & \frac{3}{6} \\
            \hhline{-||------}
              4  & \frac{4}{1} & \frac{4}{2} & \frac{4}{3} & \frac{4}{4} & \frac{4}{5} & \frac{4}{6} \\
           \hhline{-||------}
              5  & \frac{5}{1} & \frac{5}{2} & \frac{5}{3} & \frac{5}{4} & \frac{5}{5} & \frac{5}{6} \\
            \hhline{-||------}
              6  & \frac{6}{1} & \frac{6}{2} & \frac{6}{3} & \frac{6}{4} & \frac{6}{5} & \frac{6}{6} \\
            \end{tabular}

          \end{minipage}
            \end{table}
            \end{document}
